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The MG II emission in BD -0 4234
Rucinski, S. M.
The strength of the Mg II emission in this metal-poor, high-velocity binary consisting of synchronized K-type dwarfs follows the same extension of the dependence on the inverse Rossby number which holds for rapidly-rotating Population I stars. This result indicates that the efficiency of the dynamo mechanism might be independent of metal abundance.
Spectra and time variability of GX 5-1
Pietsch, W.; Brunner, H.; Kendziorra, E. +2 more
From a short observation of GX 5-1 with EXOSAT we have derived information on spectral and temporal behaviour in the energy range 1 20 keV. The source was found to be variable on time scales from 10 s to 1 h. Describing the spectrum one is forced to assume at least two spectral components. The best fit is reached using a spectrum composed of two b…
Abell 1367 and 1060 observed with EXOSAT
Westergaard, N. J.; Norgaard-Nielsen, H. U.; Hansend, L.
Two clusters of galaxies have been observed with EXOSAT to map the distribution of cool gas. For A1367 we have detected the two brightest sources found by EINSTEIN. We confirm the identification of a X-ray source with a blue object near NGC3842. By comparing the EXOSAT and the EINSTEIN count rates we can state, either that the source is variable, …
Spectral observation of the composite supernova remnant G 29.7-0.3
Braun, R.; Koch-Miramond, L.; Rocchia, R. +3 more
The X-ray properties of the supernova remnant G 29.7-0.3 are discussed based on spectral data from the EXOSAT satellite. In the 2 to 10 keV range a featureless power-law spectrum is obtained, the best-fit parameters being: energy spectral index α=-0.77, hydrogen column density on the line of sight NH=2.3.1022 cm-2.…
Mapping of the Cygnus Loop with EXOSAT
Arnaud, M.; Ballet, J.; Rocchia, R. +1 more
Three 2.104 s observations were carried out with EXOSAT on three fields following the shock from the north to the east of the Cygnus Loop supernova remnant. Due to the softness of the source, most of the photons were collected with the LE package (CMA). For each exposure we used at least three filters (4000 Å lexan, Al-Par, boron) in or…
Search for Periodicities Near 59 S in the Cos-B Gamma-Ray Data of 2CG 195+04 (geminga)
Caraveo, P. A.; Bignami, G. F.; Hermsen, W. +5 more
The COS-B data relating to five observations in the general direction of Geminga, spanning 6.7 years, were searched for pulsation near 59 s. The SAS-2 indication is not confirmed. An indication of a 59 s pulsation in the gamma ray emission from 2CG195+04 (Geminga) was reported. Early analysis of COS-B data supported the result while later improved…
Observations of Comet Crommelin. IV - Upper limit on the optical depth in the coma at ultraviolet wavelengths
Evans, A.; Zarnecki, J. C.; Bode, M. F. +2 more
The bright (V = 9.1) star SAO 152362 was observed with the long-wavelength (LWP) camera of the IUE satellite before and during a close approach by Comet Crommelin. No significant change in the ultraviolet spectrum of the star occurred during the encounter and an upper limit is set on the optical depth of the dust in the coma of the comet.
Interpretation of the measurements of secondary electron currents induced by impacts during the flyby of comet Halley
Grün, E.; Grard, R.; Apáthy, I. +3 more
The Giotto, Vega-1 and Vega-2 spacecraft flew through the environment of comet Halley at a relatively close range with velocities of the order of 70-80 km/s. The fore sections of their surface were bombarded by neutral molecules and dust grains which caused the emission of secondary electrons and sputtered ions. This paper makes use of the seconda…
An EXOSAT Observation of the Morphology of the Coronal X-Ray Emission from Algol
Parmar, A. N.; White, N. E.; Culhane, J. L. +4 more
The X-ray emission from Algol is thought to originate in a corona associated with the K star in this system. We report the results of a 35 hr continuous EXOSAT observation through secondary optical eclipse that was designed to measure the structure of the corona. No obvious X-ray eclipse was seen. The spectrum measured by the ME gives a temperatur…
Exosat observations of the supernova remnant cas a
Branduardi-Raymont, G.; Manzo, G.; Jansen, F. A. +6 more
The young supernova remnant Cas A has been observed with the imaging proportional counter (PSD) of the EXOSAT observatory. High quality spatially resolved, spectral data allow for the first time the determination of the temperature structure of the remnant. Preliminary results on the distribution of temperature and emission measureover the remnant…